1. Field
The present application relates to the manufacturing of components as well as to gas and steam turbines, and more particularly to a method of selective laser brazing.
2. Description of the Related Art
Additive Manufacturing, or 3-D printing, has recently been successfully used to ‘print’ or manufacture components directly layer by layer. This manufacturing technology enables the optimization of component design. Additive manufacturing of components includes a wide range of materials and process techniques. Two process techniques include selective laser sintering (SLS) and selective laser melting (SLM). Selective Laser Sintering (SLS) is an additive manufacturing technique that uses a laser as the power source to sinter powdered material, aiming the laser automatically at points in space defined by a three dimensional model, binding the material together to create a solid structure. Selective Laser Melting (SLM) is an additive manufacturing process that uses a three dimensional model and energy in the form of a high-power laser beam, to create the solid structure by fusing the metal powders together in the molten state. The main distinction between Selective Laser Sintering and Selective Laser Melting is that with sintering the material is not melted but is heated to the point that bonds form between particles by diffusion, while with melting, the particles are completely melted and fuse together in the molten state.
Both of these techniques, Selective Laser Sintering and Selective Laser Melting have disadvantages. For example, with Selective Laser Sintering, a fully dense component may not be achieved. After the Selective Laser Sintering process is complete, voids may exist between the particles requiring an additional process step, for example hot isostatic pressing (HIP), to press the particles together removing the voids. With Selective Laser Melting, each particle is melted and upon resolidification forms a particular crystal structure, size, and/or orientation which may not be optimized for the component. In particular, when applying the laser beam in the Selective Laser Melting technique, a layer of particles of a substrate is completely melted. Upon resolidification, the orientation of the crystal microstructure in the substrate that is melted in the process may be directional such that the properties of the layer may be different in the vertical direction than the horizontal direction. For example, the tensile strength of the layer after resolidification may be stronger in the horizontal direction as opposed to the vertical direction. A technique that would fuse the particles together without melting of the substrate material resulting in full densification and strength achievement is desired.